Choroid plexus, ependyma and arachnoidea express receptors for vitamin D: differences between "seasonal" and "non-seasonal" breeders.

Autoradiographic studies with [3H]1,25-dihydroxyvitamin D3 demonstrated nuclear high affinity binding sites (receptors) in epithelial cells of choroid plexus, ependyma and arachnoid in "seasonal" breeders of various vertebrate phyla, namely Xiphophorus helleri, Hyla crucifer, Xenopus laevis, Bufo woodhousei, Chrysemys scripta, Anolis carolinensis, Nerodia sipedon and Phodopus sungorus, but vitamin D receptors were undetectable in these tissues in non-seasonal breeders, such as zebra finch, laboratory mice and rats. Both "seasonal" and "non-seasonal" species, however, exhibited nuclear binding in distinct nuclei of CNS. The data suggest that vitamin D is involved in the regulation of certain functions at the level of the blood-brain barrier in species strongly affected by seasonal changes.